OMAP7XX: Replace omap730 references in irqs.h and all users

This patch is part of a series which removes references to omap730 in code
which is shared with omap850, replacing them with references to omap7xx.

Turns INT_730_* to INT_7XX_* for definitions in irqs.h and all users.

Signed-off-by: Alistair Buxton <a.j.buxton@gmail.com>
Reviewed-by: Zebediah C. McClure <zmc@lurian.net>